Testing Testing

Exposure Comp

noreply@blogger.com (baobab) — Sat, 23 Feb 2008 02:50:00 +0000

This one is for danthro.

Here are shots of the lobster weathervane with the camera set to aperture priority (auto shutter speed), and using exposure compensation.

F 5.6 ... 56 mm ... 1/1000 sec

[no exposure comp]

F 7.1 ... 56 mm ... 1/500 sec

0.67 step exposure comp

F 7.1 ... 60 mm ... 1/320 sec
1.00 step exposure comp

Though the aperture was wide open the first shot was too dark - no detail. Even the sky seems gloomy.

In the second shot I upped the F-stop to increase depth of field. All things being equal the camera would have reduced shutter speed to obtain the same exposure as the first shot
[higher F-stop = smaller aperture, which is a little counterintuitive but Wikipedia provides an explanation].

I didn't want another dark shot, so I set exposure comp to +0.67. This increased the amount of light captured by the camera, showing detail on the lobster and building while still keeping rich colour in the sky.

In the third shot I upped exposure comp once more (my camera does it in steps of a third of a stop) but this time although there was yet more colour in the building the sky and clouds started looking blown out.

All these photos are straight from the camera, simply resized to reduce download time.

I went with the middle shot as my Goldilocks shot - the other two were really used to bracket it and ensure that I calibrated correctly. The composition in the last shot is a little sloppy: if it were a keeper I'd rotate and crop it to remove the lower left distraction.

Depth of Field

noreply@blogger.com (baobab) — Fri, 16 Nov 2007 21:00:00 +0000

Back on the topic of the Nikkor 18 - 200, here's a shot showing depth of field at extended zoom:

F 5.6 ... 200 mm ... 1/60 sec

These are the same shot. The first image has been compressed to save bytes. The second image is a crop; if you click on it you will see it at 100% relative to the original.

This shot was taken on a windy day - I missed the moment when the leaf was fully vertical but am nonetheless impressed by the lens's auto-focus working with the moving target.

Having used the lens for a couple of months now, I really like the large aperture bokeh at extended zoom, though the narrow depth of field does require precise attention to focus, as the following shots show:

F 5.6 ... 120 mm ... 1/160 sec

Despite the shorter zoom, the area of sharpest focus is at the intersection of bricks between the leaves. Ho hum... boring.

F 5.6 ... 200 mm ... 1/200 sec

This time the leaf is in focus and the brick blurs slightly. Once again an uncompressed crop to show the detail at 100%.

Others II

noreply@blogger.com (baobab) — Fri, 05 Oct 2007 22:56:00 +0000

Another shot I really like from Photonodie, whom I found via play.blogger

It appeals to the African (bushbaby) in me.

And on the topic of my own work, the Prague/Czech photos are now in the gallery.

Others' work

noreply@blogger.com (baobab) — Wed, 03 Oct 2007 23:22:00 +0000

Surfing around play.blogger when I should have been working today I came across this shot from the Idolos del Futuro blog:

Unfortunately I don't speak Spanish so have no idea what the story is about (and I hope the author doesn't mind my embedding the image here in a more easily viewable format).

Anyway, I like the energy and the colour... who knew two middle-aged men in suits could be so interesting.

Light and Timing

noreply@blogger.com (baobab) — Fri, 14 Sep 2007 23:15:00 +0000

A couple of shots showing the challenge of contrast:

F 10 .. 18 mm .. 1/250 sec

F 10 .. 18 mm .. 1/400 sec

The first shot is a yawn: underexposed in the nearground, overexposed in the farground. Though it's not technically perfect I like the drama of the second shot, taken a few minutes later as a cloud sailed by. The result makes the buildings pop far more, and the faster shutter speed keeps the background from fading out.

In the Field: Exposure

noreply@blogger.com (baobab) — Fri, 14 Sep 2007 23:00:00 +0000

The cathedral of St Vitus is an imposing Gothic edifice at the castle in Prague. It is vast and gloomy: a great setting for the Addams family, but a challenge to photograph on a very bright day. So I fiddled with the exposure and got the following set of photographs:

F 10 .. 24 mm .. 1/320 sec

F 7.1 .. 18 mm .. 1/500 sec

F 7.1 .. 18 mm .. 1/200 sec

Shooting a dark building against a bright sky is difficult... and the sky gets that weird wash-out of colour closer to the (invisible) sun. Adjusting the exposure almost completely erased (overexposed) the colour of the sky, though the building's detail was far clearer. None of them great shots. For these shots the only filter used was a (UV) skylight.

Turning around and shooting a light building with my back to the sun resulted in these shots, the first at the same settings as the final shot of St Vitus above:

F 7.1 .. 18 mm .. 1/200 sec

F 7.1 .. 18 mm .. 1/1250 sec

Amazing what a difference lighting and reflective surfaces make!

Depth of Field / Zoom

noreply@blogger.com (baobab) — Tue, 11 Sep 2007 00:03:00 +0000

Here's a study in how the depth of field alters as one adjusts the zoom.

All photos were taken from the same spot, using a fixed aperture (F 5.6). The first two involved focusing in turn on neighbouring flowers to give a sense of the very narrow constraints on depth of field at 200 mm. Subsequent shots all focused on the forward flower.

Of note - when using the maximal zoom, exactly *what* you focus on is very important. At wide angles focusing anywhere roughly in the general area one wants will do. So no snapshots / action shots at great zoom.

F 5.6 .. 200 mm .. 1/160 sec

F 5.6 .. 200 mm .. 1/125 sec

F 5.6 .. 105 mm .. 1/160 sec

F 5.6 .. 56 mm .. 1/125 sec

F 5.6 .. 27 mm .. 1/125 sec

F 5.6 .. 18 mm .. 1/80 sec
original jpg

Photo Blog

noreply@blogger.com (baobab) — Mon, 10 Sep 2007 15:11:00 +0000

As if three blogs weren't sufficient, I've started an echte photo blog at http://baobab.aminus3.com/ - also titled Images Across The Earth. The idea here is to post a shot a day, which may be a challenge since I tend to have a python approach to photography. It's probably good discipline to keep one's eye in: I'm just starting to get back to composition after focusing on pushing the edge of the technical envelope with the new lens.

The difference between the Aminus3 ["A minus 3"] blog and the original IATE blogger blog is that the former is really designed to show off individual photographs, while the latter is intended for story-telling, supporting the travelogue. I think they'll complement one another.

Stay tuned for some thoughts on the recent shots on A-3. I intend to upload more of the best archive shots once I dig out the source files.

Shadow Birds

noreply@blogger.com (baobab) — Sat, 08 Sep 2007 15:02:00 +0000

In addition to the unattractive but technically interesting photos of geese on the kaleidoscope water, I got some cool shots of silhouetted birds. My favourites are posted on Images Across The Earth.

The in-flight shots were technically tricky because the light was fading rapidly, the birds were some distance away, and they were moving fast.

Compare the detail below with the second shot in the gallery, which was taken twenty minutes earlier.

F 11 .. 200 mm .. 1/60 sec
(detail)

Technical specs for the gallery shot: F 13 .. 135 mm .. 1/200 sec (detail). The increased shutter speed and different angle captured individual feathers in motion rather than a full-wing blur.

I also got some interesting shots of birds on the water. At a glance the first gallery shot looks as though it is a single bird with its shadow/reflected in the water, but in fact there are two birds:

F 5.6 .. 200 mm .. 1/60 sec
(detail)

Technical specs for the gallery shot: F 5.6 .. 200 mm .. 1/80 sec (detail). The two shots were taken in rapid succession.

Finally, a detail that shows off more of the 18 - 200 lens' capabilities:

F 7.1 .. 170 mm .. 1/60 sec
(detail)

Click the image to see the full-size version. The camera did a fantastic job of capturing the reflected light and texture of the water. Note the concentric ripples around the righthand bird, overlaid on the river's natural weave. This is a full-width version of the original shot, simply cropped to remove the less interesting foreground/background that was out of field.

Dizzy Ducks (actually geese)

noreply@blogger.com (baobab) — Fri, 07 Sep 2007 18:52:00 +0000

This time, a couple of dizzying shots using the 18 - 200 mm lens.

The bokeh gets noticeably more intense at greater zoom, in this case exacerbated by the reflected light, the moving water and the slow shutter speed (VR accommodates camera vibration, not a moving environment).

At an extreme this could be used to make deliberately artsy photos. A faster shutter speed and polarizing filter would have flattened the photos into dull shots of geese.

F 5.6 .. 135 mm .. 1/30 sec
original jpg

F 5.6 .. 200 mm .. 1/30 sec

original jpg

More (18 - 70) River Shots

noreply@blogger.com (baobab) — Fri, 07 Sep 2007 17:20:00 +0000

A little later that afternoon, still with the 18 - 70, I took a series of shots varying the aperture.

The interesting thing here is the comparison with the 18 - 200 mm lens in terms of bokeh and vibration blur. I'll have to take the two lenses out and do an apples-to-apples comparison of identical shots.

Notes:
F5.6 - bright (red, yellow) colours render best but bokeh is distracting.
F9 - probably the best shot overall: you'd get a similar effect using the camera's landscape program.
F14 - slower shutter speed results in obvious vibration blur: 18 - 200 VR would solve this.

F 5.6 .. 70 mm .. 1/125 sec
original jpg

F 9 .. 70 mm .. 1/100 sec
original jpg

F 14 .. 70 mm .. 1/50 sec
original jpg

F 14 .. 70 mm .. 1/30 sec
original jpg

River of Light

noreply@blogger.com (baobab) — Fri, 07 Sep 2007 16:44:00 +0000

A couple of weeks ago I was out with my trusty 18 - 70 Af-S 1:3.5-4.5G DX Nikkor lens, which is what I used for 90% of our China and Tibet photos (and 99% of those that turned out well). It's a great lens which I'd highly recommend.

Along with the usual pretty shots of the Charles River and Harvard there were some technically interesting photos in the set. The blinding reflection of the afternoon sun tricked the camera into using a high speed for a small aperture. The result was good depth of field and an interesting blend of [technically] over-exposed, under-exposed, silhouetted and goldilocks elements in the picture.

Notes:
Composition was very quick and somewhat haphazard since the reflection was blinding and I didn't want to burn out my retina or the sensor.

fwiw, I have also always really liked the way this lens renders water.

F 16 .. 50 mm .. 1/400 sec

F 11 .. 62 mm .. 1/640 sec

Somerville Throne

noreply@blogger.com (baobab) — Thu, 06 Sep 2007 21:28:00 +0000

Outside the Davis Square post office today, a well-branded portaloo. Not of particular technical note, but entertaining.

Of note - good depth of field with a large aperture at 55 mm zoom.

F 5 .. 55 mm .. 1/320 sec

original jpg

Nighttime Harvard Square

noreply@blogger.com (baobab) — Thu, 06 Sep 2007 18:40:00 +0000

Out again with the new lens yesterday evening (again a little late, but that just creates great test conditions).

Of note: these shots focused on "the garage" sign, and were handheld after dark. For the two landscape-oriented photos there's a distinct difference in crispness in the lettering at the centre of the shot, while the non-central elements appear similar. In the first shot slight blur is due to vibration; in the second it is depth of field/bokeh.

In the portrait-oriented shot it's worth noting the detail of the reflection at the lower left and the legibility of the unilluminated street signs. This used a relatively slow shutter speed, so moving traffic and pedestrians are slightly blurred. VR did a great job again.

F 9 .. 28 mm .. 1/3 sec
original jpg

F 5.6 .. 28 mm .. 1/8 sec

original jpg

F 10 .. 36 mm .. 1/4 sec
original jpg

Ghost Flowers

noreply@blogger.com (baobab) — Tue, 04 Sep 2007 15:49:00 +0000

Just before heading in I caught sight of some sunflowers in lamplight. These ghost flowers were the result:

F 5.6 .. 200 mm .. 1.6 sec

Low Light Photography

noreply@blogger.com (baobab) — Tue, 04 Sep 2007 14:11:00 +0000

Yesterday evening I went out a little too late... which meant that I didn't get great art shots, but I did have the chance to try out the Nikkor's vibration reduction (VR) technology, as well as to make some 'artsy' shots.

All of these were hand-held with VR (vibration reduction) on. Aperture priority unless otherwise noted.

Of note: Vibration Reduction ROCKS!

Context for these shots: Danehy Park, Cambridge MA, shortly after sunset.

F 5 .. 18 mm .. 1/100 sec

A couple of teenage girls were rolling down the hill:

F 5.6 .. 135 mm .. 1/13 sec
original jpg

On the field at the bottom of the hill some boys were kicking a soccer ball around:

F 5.6 ..170 mm .. 1/13 sec
original jpg

F 8 .. 29 mm .. 2/5 sec
original jpg

F 13 .. 29 mm .. 2/5 sec
original jpg

Nikon 18 - 200 mm Lens

noreply@blogger.com (baobab) — Tue, 04 Sep 2007 12:47:00 +0000

Before the next exotic trip I want to get to grips with the new lens. Yesterday I took it for a spin, and here are the results:

All photos Nikon D70, Nikkor 18 - 200 mm lens.

Busa Farm, Lexington MA USA

This sequence was taken standing on the same spot, using the same f-stop (aperture priority), in bright daylight (auto white balance). The original full-size photos are hosted by Pixamo.

Of note: very crisp focus, bokeh increases dramatically with zoom. Almost no bokeh at wide angles.

F 5.6 .. 150 mm .. 1/1250 sec

original jpg

F 5.6 .. 80 mm .. 1/1250 sec
original jpg

F 5.6 .. 26 mm .. 1/2000 sec
original jpg

Shadow Geese

noreply@blogger.com (baobab) — Sat, 01 Sep 2007 16:04:00 +0000

Images Across The Earth

New Blog

noreply@blogger.com (baobab) — Sat, 01 Sep 2007 12:41:00 +0000

Rather than cluttering up baobabtravels with gadgets and gizmos, herewith a new space for playing with toys...